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* [PATCH net 1/1] net sched actions: fix GETing actions
@ 2016-09-08 12:12 Jamal Hadi Salim
  2016-09-08 17:12 ` Cong Wang
  0 siblings, 1 reply; 4+ messages in thread
From: Jamal Hadi Salim @ 2016-09-08 12:12 UTC (permalink / raw)
  To: davem; +Cc: netdev, xiyou.wangcong, Jamal Hadi Salim

From: Jamal Hadi Salim <jhs@mojatatu.com>

Example of what broke:
...add a gact action to drop
sudo $TC actions add action drop index 10
...now retrieve it, looks good
sudo $TC actions get action gact index 10
...retrieve it again and find it is gone!
sudo $TC actions get action gact index 10

Fixes: f07fed82ad79 ("net_sched: remove the leftover cleanup_a())

Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 net/sched/act_api.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index d09d068..d4b4704 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -612,6 +612,8 @@ int tcf_action_init(struct net *net, struct nlattr *nla,
 			goto err;
 		}
 		act->order = i;
+		if (ovr)
+			act->tcfa_refcnt+=1;
 		list_add_tail(&act->list, actions);
 	}
 	return 0;
@@ -856,6 +858,15 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
 	return ret;
 }
 
+static void cleanup_a(struct list_head *actions)
+{
+	struct tc_action *a, *tmp;
+
+	list_for_each_entry_safe(a, tmp, actions, list) {
+		list_del(&a->list);
+	}
+}
+
 static int
 tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
 	      u32 portid, int event)
@@ -883,6 +894,7 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
 			goto err;
 		}
 		act->order = i;
+		act->tcfa_refcnt+=1;
 		list_add_tail(&act->list, &actions);
 	}
 
@@ -892,10 +904,12 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
 		ret = tcf_del_notify(net, n, &actions, portid);
 		if (ret)
 			goto err;
+		cleanup_a(&actions);
 		return ret;
 	}
 err:
 	tcf_action_destroy(&actions, 0);
+	cleanup_a(&actions);
 	return ret;
 }
 
@@ -931,10 +945,10 @@ tcf_action_add(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
 	LIST_HEAD(actions);
 
 	ret = tcf_action_init(net, nla, NULL, NULL, ovr, 0, &actions);
-	if (ret)
-		return ret;
 
-	return tcf_add_notify(net, n, &actions, portid);
+	ret = tcf_add_notify(net, n, &actions, portid);
+	cleanup_a(&actions);
+	return ret;
 }
 
 static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n)
-- 
1.9.1

^ permalink raw reply related	[flat|nested] 4+ messages in thread

* Re: [PATCH net 1/1] net sched actions: fix GETing actions
  2016-09-08 12:12 [PATCH net 1/1] net sched actions: fix GETing actions Jamal Hadi Salim
@ 2016-09-08 17:12 ` Cong Wang
  2016-09-11 16:30   ` Jamal Hadi Salim
  0 siblings, 1 reply; 4+ messages in thread
From: Cong Wang @ 2016-09-08 17:12 UTC (permalink / raw)
  To: Jamal Hadi Salim; +Cc: David Miller, Linux Kernel Network Developers

On Thu, Sep 8, 2016 at 5:12 AM, Jamal Hadi Salim <jhs@mojatatu.com> wrote:
> From: Jamal Hadi Salim <jhs@mojatatu.com>
>
> Example of what broke:
> ...add a gact action to drop
> sudo $TC actions add action drop index 10
> ...now retrieve it, looks good
> sudo $TC actions get action gact index 10
> ...retrieve it again and find it is gone!
> sudo $TC actions get action gact index 10

This changelog sucks, it only tells the phenomenon of the bug,
never explains what causes the bug, which is crucial for review.

>
> Fixes: f07fed82ad79 ("net_sched: remove the leftover cleanup_a())
>
> Signed-off-by: Jamal Hadi Salim <jhs@mojatatu.com>
> ---
>  net/sched/act_api.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
> index d09d068..d4b4704 100644
> --- a/net/sched/act_api.c
> +++ b/net/sched/act_api.c
> @@ -612,6 +612,8 @@ int tcf_action_init(struct net *net, struct nlattr *nla,
>                         goto err;
>                 }
>                 act->order = i;
> +               if (ovr)
> +                       act->tcfa_refcnt+=1;

This looks like not relevant to commit f07fed82ad79 at all?


>                 list_add_tail(&act->list, actions);
>         }
>         return 0;
> @@ -856,6 +858,15 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions,
>         return ret;
>  }
>
> +static void cleanup_a(struct list_head *actions)
> +{
> +       struct tc_action *a, *tmp;
> +
> +       list_for_each_entry_safe(a, tmp, actions, list) {
> +               list_del(&a->list);
> +       }

After my patches, all the action lists are now temporary,
you didn't explain why we should remove an action from
a temporary list, they should just come and go, since
we call ist_add() every time.

Did see any list corruption or kernel crash (your changelog
didn't say so)?


> +}
> +
>  static int
>  tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>               u32 portid, int event)
> @@ -883,6 +894,7 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>                         goto err;
>                 }
>                 act->order = i;
> +               act->tcfa_refcnt+=1;


Maybe we only need to fixup the refcnt without touching list,
from my quick observation to your bug report (again, you didn't explain).


>                 list_add_tail(&act->list, &actions);
>         }
>
> @@ -892,10 +904,12 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>                 ret = tcf_del_notify(net, n, &actions, portid);
>                 if (ret)
>                         goto err;
> +               cleanup_a(&actions);
>                 return ret;
>         }
>  err:
>         tcf_action_destroy(&actions, 0);
> +       cleanup_a(&actions);
>         return ret;
>  }
>
> @@ -931,10 +945,10 @@ tcf_action_add(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>         LIST_HEAD(actions);
>
>         ret = tcf_action_init(net, nla, NULL, NULL, ovr, 0, &actions);
> -       if (ret)
> -               return ret;
>
> -       return tcf_add_notify(net, n, &actions, portid);
> +       ret = tcf_add_notify(net, n, &actions, portid);
> +       cleanup_a(&actions);
> +       return ret;
>  }
>
>  static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n)
> --
> 1.9.1
>

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH net 1/1] net sched actions: fix GETing actions
  2016-09-08 17:12 ` Cong Wang
@ 2016-09-11 16:30   ` Jamal Hadi Salim
  2016-09-11 18:56     ` Cong Wang
  0 siblings, 1 reply; 4+ messages in thread
From: Jamal Hadi Salim @ 2016-09-11 16:30 UTC (permalink / raw)
  To: Cong Wang; +Cc: David Miller, Linux Kernel Network Developers

On 16-09-08 01:12 PM, Cong Wang wrote:

>> +}
>> +
>>  static int
>>  tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>>               u32 portid, int event)
>> @@ -883,6 +894,7 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n,
>>                         goto err;
>>                 }
>>                 act->order = i;
>> +               act->tcfa_refcnt+=1;
>
>
> Maybe we only need to fixup the refcnt without touching list,
> from my quick observation to your bug report (again, you didn't explain).
>

Yes, you are correct. clearing the list is unnecessary since it is
temporary. When i get the chance i will fix it up, test and resubmit.

What do you want the commit message to say? It shows an example because
the functionality broke.

cheers,
jamal

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH net 1/1] net sched actions: fix GETing actions
  2016-09-11 16:30   ` Jamal Hadi Salim
@ 2016-09-11 18:56     ` Cong Wang
  0 siblings, 0 replies; 4+ messages in thread
From: Cong Wang @ 2016-09-11 18:56 UTC (permalink / raw)
  To: Jamal Hadi Salim; +Cc: David Miller, Linux Kernel Network Developers

On Sun, Sep 11, 2016 at 9:30 AM, Jamal Hadi Salim <jhs@mojatatu.com> wrote:
>
> What do you want the commit message to say? It shows an example because
> the functionality broke.

I expect it to explain why we need to increase that refcnt for GET
and how we missed it. Also need to find a right commit to blame. ;)

Thanks.

^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2016-09-11 18:56 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2016-09-08 12:12 [PATCH net 1/1] net sched actions: fix GETing actions Jamal Hadi Salim
2016-09-08 17:12 ` Cong Wang
2016-09-11 16:30   ` Jamal Hadi Salim
2016-09-11 18:56     ` Cong Wang

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